Image sensors are ubiquitous. They are widely used in many different types of applications. In certain types of applications such as the medical field, the size and image quality of image sensors are particularly important. Consequently, there is a demand for the miniaturization of image sensors without compromising image quality.
FIG. 1 is a circuit diagram illustrating conventional shared pixel architecture 100. Shared pixel architecture 100 includes pixel circuitry 105 of two pixels within an image sensor. Each pixel circuitry 105 includes a photodiode region (“PD”) and transistor circuitry that provides a variety of functionality for regular operation of each pixel. For example, pixel circuitry 105 may include circuitry to commence an accumulation of image charge within photodiode region PD, to reset the image charge within photodiode region PD, to transfer the image charge to a storage node (“MEM”), and to transfer the image charge to a floating diffusion region (“FD”). To control this functionality, pixel circuitry 105 requires wiring that consumes valuable space within each pixel at the expense of photodiode region PD. Accommodating this wiring within each pixel reduces the area of photodiode region PD that is exposed to light, thereby reducing the fill factor of the pixel and degrading pixel sensitivity and image quality.